Use serde derive feature. (#2351)

* core/primitives

* sr-primitives

* sr-primitives

* srml-treasury

* substrate-executor

* substrate-keystore

* network-libp2p

* substrate-service

* srml-system

* substrate-rpc

* sr-version

* substrate-telemetry

* substrate-test-runtime

* substrate-transaction-pool

* node-template-runtime

* node-primitives

* srml-consensus

* srml-contract

* srml-democracy

* srml-finality-tracker

* srml-grandpa

* srml-metadata

* srml-support

* Clean

* Update locks

substrate/core/rpc/src/system/helpers.rs

@@ -17,7 +17,7 @@
 //! Substrate system API helpers.
 
 use std::fmt;
-use serde_derive::{Serialize};
+use serde::Serialize;
 use serde_json::{Value, map::Map};
 
 /// Node properties